Centrifugal compressors pump a sucked fluid by using a centrifugal force on an impeller that rotates along with a rotation shaft. Among such centrifugal compressors, a single-shaft multi-stage centrifugal compressor has been well known in which a plurality of impellers are provided at a plurality of states along the axial direction to compress a fluid in a stepwise manner. By employing such a configuration, a high compression ratio can be easily obtained for the fluid.
Further, a conventional centrifugal compressor as described above is disclosed in Patent Document 1, for example.